How to set runlevel with chkconfig

This implementation of chkconfig was inspired by the chkconfig command present in the IRIX operating system. Rather than maintaining configuration information outside of the /etc/rc[0-6].d hierarchy, however, this version directly manages the symlinks in /etc/rc[0-6].d.

In Redhat Linux you have a powerfull tool called chkconfig, you can list all the services with:
#chkconfig --list
To see the services started in runlevel 3:
#chkconfig --list | grep 3:on

To turn off a service in all the runlevels:
#chkconfig pcmcia off

Turn off a service in a desired runlevel:
#[root@monitor1]# chkconfig --list | grep hpoj
hpoj 0:off 1:off 2:on 3:on 4:on 5:on 6:off
#[root@monitor1]# chkconfig --level 3 hpoj off
#[root@monitor1 rc3.d]# chkconfig --list | grep hpoj
hpoj 0:off 1:off 2:on 3:off 4:on 5:on 6:off


If you want to add a new service, you created the /etc/rc.d/init.d/ file and now you wans to manage the service, configure it to start and stop on desired runlevels.

Edit the /etc/rc.d/init.d/service-name file, and add this line on the top:

#!/bin/bash
# chkconfig: 2345 55 25
# description: A service that does powerful things
#

This is a description of what this line does:
# chkconfig: 2345 55 25
             |   |  |
             |   |  priority for kill scripts
             |   |
             |   priority for start scripts
             |
             run levels at which to start service

Then execute, for example, adding the qmail service:
#[root@monitor1 init.d]# chkconfig --add qmail
#[root@monitor1 init.d]# chkconfig --list qmail
qmail           0:off   1:off   2:off   3:on    4:off   5:on    6:off

Now configure it to start on desired runlevels !